Window Fan

ABSTRACT

A dual window fan having a rectangular body adapted to engage a window, two fan heads pivotably engaging the body independently of each other about a vertical pivot axis from aiming directly outwardly normal to the body to aiming inwardly through a pivot angle of at least 225 angular degrees.

FIELD OF THE INVENTION

The present invention is related to air-moving appliances. More specifically, it is related to window fans. Even more specifically, it is related to dual window fans.

BACKGROUND

Window fans are well known. Such fans of the prior art are placed in an open or partially open window, and in the case of a sliding or casement window the window is then partially closed against the fan. The fan is then energized to either blow fresh air into the room or to blow stale air out of the room.

Dual window fans are also known and include two side-by-side fans which are intended to provide increased airflow.

Dual window fans are also known in which one or both of the fans are electrically reversible to allow for a selected one of inflow or outflow.

A drawback in such arrangements is that the airflow into the room creates positive air pressure within the room which then impedes further inflow, and the airflow out of the room creates negative air pressure within the room which then impedes further outflow.

Dual window fans are also known in which the fans are each independently electrically reversible to allow for simultaneous inflow and outflow to thereby reduce such impedance.

Among the drawbacks in such arrangement are that reversible motors are more complex and expensive to manufacture, that fan blades are most efficient and effective when designed to move air in a single direction and when moving air in that direction, and that motors are most efficient and effective when coupled with a single-direction fan blade operating in its intended direction

There exists a need for, and it is an object of the invention to provide, a window fan which allows air exchange between the room and outdoors without requiring reversible motors or 2-way fan blades.

There also exists a need for, and it is an object of the invention to provide, such a window fan which allows for directional adjustment of the incoming airflow.

There also exists a need for, and it is an object of the invention to provide, such a window fan which allows for the directional adjustment to be into a plurality of incoming airflow directions.

Further needs and objects exist which are addressed by the present invention, as may become apparent upon review of the included disclosure of exemplary embodiments thereof.

SUMMARY OF THE INVENTION

The invention may be embodied in or practiced using an electrical window fan having two pivotable fan heads which are each arranged to blow air therethrough and which each may be pivoted independently of the other both leftwardly or rightwardly to direct incoming airflow in a selected direction, or which each may be pivoted independently of the other to face outdoors and cause an outflow, and which may be pivoted relative to each other so that one causes inflow while the other causes outflow.

The invention may also be embodied in or practiced using a window fan having a rectangular body adapted to engage a window within an opening thereof and a plurality of fan heads pivotably engaging the body independently of each other each adapted to cause airflow through the body either inwardly when pivoted inwardly and outwardly when pivoted outwardly. The fan heads may each be pivotable relative to the body about a vertical pivot axis. The fan heads may each be pivotable from aiming directly outwardly normal to the body to aiming inwardly through a pivot angle of at least 225 angular degrees. Each fan head may include a non-reversible motor coupled to a fan blade and adapted to rotate the fan blade only in a single rotational direction to cause an airflow through the associated fan head only in one axial direction relative to the associated fan head. Each fan head may have intake and exhaust openings and each fan blade may have five fan vanes equally-spaced about the blade and shaped with a concave downwind face and convex upwind face for optimal airflow from the intake opening to the exhaust opening. Each fan head may have spirally-curved intake and exhaust vanes and cylindrical duct surrounding its associated fan blade, the intake and exhaust vanes curved in the single rotational direction, such that the rotating fan blade, duct, and vanes cooperate to cause helical collimation of the airflow. The window fan may have expandible side panels adapted for extension from the body to cover any portion of the opening that the body does not. The window fan may have bug screens adapted for selective affixation to the body over the intake opening of each fan head and dome shaped to allow pivoting of the fan head.

Further features and aspects of the invention are disclosed with more specificity in the Detailed Description and accompanying drawings of an exemplary embodiment provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the invention can be better understood with reference to the included Drawings showing an exemplary embodiment for practicing the invention which corresponds to the accompanying Detailed Description. The components in the Drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention. Moreover, like reference numerals in the Drawings designate corresponding parts throughout the several views.

FIG. 1 is a perspective view of a dual window fan with both fans blowing inward;

FIG. 2 is a perspective view of the window fan of FIG. 1 with one fan blowing inward and one blowing outward;

FIG. 3 is a is a perspective view of the window fan of FIG. 1 with both fans blowing inward but pivoted in different directions;

FIG. 4 is a perspective view of a fan blade of the of the window fan of FIG. 1;

FIG. 5 is a side view of a fan blade of the of the window fan of FIG. 1;

FIG. 6 is a top view of the window fan of FIG. 1 with one fan blowing inward and one blowing outward;

FIG. 7 is a top view of the window fan of FIG. 1 with one fan blowing inward and one blowing outward;

FIG. 8 is a top view of the window fan of FIG. 1 with one fan blowing inward and one blowing outward;

FIG. 9 is a top view of the window fan of FIG. 1 with one fan blowing inward and one blowing outward;

FIG. 10 is a top view of the window fan of FIG. 1 with one fan blowing inward and one blowing outward;

FIG. 11 is a top view of the window fan of FIG. 1 with one fan blowing inward and one blowing outward;

FIG. 12 is a cross-section through the window fan of FIG. 1 taken at line 12-12 of FIG. 1;

FIG. 13 is a front view of a bug screen for the window fan of FIG. 1; and

FIG. 14 is a side view of the bug screen of FIG. 13.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

A window fan 100 is shown in FIGS. 1 through 12. The fan includes rectangular body 102 having left fan head 104L and 104R and expandible side panels 106L and 106R. Each fan head has top and bottom pivot shafts 108T and 108B which rotate with pivot shaft receivers 110T and 110B, respectively, of the body, allowing the fan heads to each rotate at least from the positions shown in FIG. 8, through the positions shown in FIG. 7, to the positions shown in FIG. 9. In FIG. 8, the fan heads are both aimed straight outwardly at 90 degrees relative to the body. In FIG. 7 the fan heads are both aimed straight inwardly at 90 degrees relative to the body. And in FIG. 9 the fan heads are aimed inwardly but diverge 90 degrees from each other and aim at 45 degrees relative to the body. The pivot shafts and pivot shaft receivers define a vertical pivot axis 111 about which the fan heads are capable of pivoting at least 225 degrees, the left fan head pivoting 225 degrees clockwise in the top view from FIG. 8 to FIG. 9 and the right fan head pivoting 225 degrees counter-clockwise in the top view from FIG. 8 to FIG. 9.

The vertical pivot axis enables an axial incoming airflow to be aimed at any of a wide angle of directions withing the room to cool persons regardless of their position in the room, whereas an alternative horizontal pivot angle would only allow upward and downward pivoting which could only cool persons directly in front of the fan.

The rectangular body is adapted for placement into the opening of a partially or fully-opened window. In the case where the opening is wider than the body, the expandible side panels may be extended from the sides of the body as needed to cover any portion of the opening that the body does not.

Each fan head includes a motor 112 and a fan blade 114. While these are identical in each fan head in both shape and direction, it is anticipated that one blade/motor could be configured to rotate opposite the other, with one fan blade being the mirror image of the other, if desired for symmetry. The blade rotates clockwise when viewed from the front as of FIG. 5.

The fan blade is shaped for optimal, most efficient, and fastest airflow from the motor side through the blade. In other words, it is a “one-way” blade. This is accomplished by the concavity R1 of the forward (downwind) face 116 and the convexity R2 or rear (upwind) face 117 of the fan blade vanes 118 as best seen in FIGS. 4 and 12, and the more acute forward tip 120 of each vane. Such a fan blade is thereby asymmetrical in the axial direction of airflow to cause a much higher and more efficient airflow in the intended direction versus the hypothetical opposite direction, whereas a two-way blade would be symmetrical in the axial direction of airflow to cause equal but lower airflow efficiencies in either direction.

Each fan includes five fan blade vanes equally spaced around the blade, which is found superior in achieving proper balance of the blade during rotation because slight unintended inequalities between the blades are more easily forgiven be such an uneven and pentagonally-disposed arrangement.

The pivoting of the head to aim either inward or outward as desired while the motor/blade rotates in the same direction at all times is thereby superior to the alternative of reversing motor/blade rotation because a more expensive and less reliable reversible motor and a less efficient two-way blade are not needed.

The intake face 122 and exhaust face 124 of each fan head include spirally-curved vanes 126 which curve in the direction of the motor/blade rotation and the fan blade is positioned within cylindrical duct 128. This causes a helical collimation of the exhausted airflow 130, which enables it to reach further into the room at a higher velocity during inward operation than would the turbulent airflow from a common free-flow fan. Such a collimated airflow is quieter than a common turbulent airflow. And this is accomplished without sacrificing the air volume, which is important for ventilation.

FIGS. 13 and 14 show a snap-in bug screen 200 for optional use with the window fan. Two such screens may be affixed to the body to surround the intake side of each fan head. The screen is dome-shaped to avoid the fan head regardless of its pivoted position. The screen includes snap-hooks 202 for engaging the body, a plastic frame 204, and mesh screening 206 porous enough to allow airflow there-through but blocking enough to prevent bugs from passing therethrough.

Various changes in form and detail may be made without departing from the spirit and scope of the invention, so the invention should therefore only be considered according to the following claims, including all equivalent interpretation to which they are entitled. 

I claim:
 1. A window fan comprising: a rectangular body adapted to engage a window within an opening thereof; a plurality of fan heads pivotably engaging the body independently of each other each adapted to cause airflow through the body either inwardly when pivoted inwardly and outwardly when pivoted outwardly.
 2. The window fan of claim 1 wherein the fan heads are each pivotable relative to the body about a vertical pivot axis.
 3. The window fan of claim 2 wherein the fan heads are each pivotable from aiming directly outwardly normal to the body to aiming inwardly through a pivot angle of at least 225 angular degrees.
 4. The window fan of claim 3 wherein each fan head comprises a non-reversible motor coupled to a fan blade and adapted to rotate the fan blade only in a single rotational direction to cause an airflow through the associated fan head only in one axial direction relative to the associated fan head.
 5. The window fan of claim 4 wherein each fan head comprises intake and exhaust openings and each fan blade comprises fan vanes shaped with a concave downwind face and convex upwind face for optimal airflow from the intake opening to the exhaust opening.
 6. The window fan of claim 5 wherein each fan head comprises spirally-curved intake and exhaust vanes and cylindrical duct surrounding its associated fan blade, the intake and exhaust vanes curved in the single rotational direction, such that the rotating fan blade, duct, and vanes cooperate to cause helical collimation of the airflow.
 7. The window fan of claim 6 wherein each fan blade comprises five equally-spaced fan blade vanes.
 8. The window fan of claim 7 further comprising expandible side panels adapted for extension from the body to cover any portion of the opening that the body does not.
 9. The window fam of FIG. 8 further comprising bug screens adapted for selective affixation to the body over the intake opening of each fan head and dome shaped to allow pivoting of the fan head.
 10. The window fan of claim 1 wherein the fan heads are each pivotable from aiming directly outwardly normal to the body to aiming inwardly through a pivot angle of at least 225 angular degrees.
 11. The window fan of claim 10 wherein each fan head comprises a non-reversible motor coupled to a fan blade and adapted to rotate the fan blade only in a single rotational direction to cause an airflow through the associated fan head only in one axial direction relative to the associated fan head.
 12. The window fan of claim 11 wherein each fan head comprises intake and exhaust openings and each fan blade comprises fan vanes shaped with a concave downwind face and convex upwind face for optimal airflow from the intake opening to the exhaust opening.
 13. The window fan of claim 12 wherein each fan head comprises spirally-curved intake and exhaust vanes and cylindrical duct surrounding its associated fan blade, the vanes curved in the single rotational direction, such that the rotating fan blade, duct, and vanes cooperate to cause helical collimation of the airflow.
 14. The window fan of claim 13 wherein each fan blade comprises five equally-spaced fan blade vanes.
 15. The window fan of claim 14 further comprising expandible side panels adapted for extension from the body to cover any portion of the opening that the body does not.
 16. The window fam of FIG. 15 further comprising bug screens adapted for selective affixation to the body over the intake opening of each fan head and dome shaped to allow pivoting of the fan head.
 17. The window fan of claim 1 wherein each fan head comprises intake and exhaust openings and each fan blade comprises fan vanes shaped with a concave downwind face and convex upwind face for optimal airflow from the intake opening to the exhaust opening.
 18. The window fan of claim 17 wherein each fan head comprises spirally-curved intake and exhaust vanes and cylindrical duct surrounding its associated fan blade, the vanes curved in the single rotational direction, such that the rotating fan blade, duct, and vanes cooperate to cause helical collimation of the airflow.
 19. The window fan of claim 18 wherein each fan blade comprises five equally-spaced fan blade vanes.
 20. The window fan of claim 19 further comprising expandible side panels adapted for extension from the body to cover any portion of the opening that the body does not.
 21. The window fam of FIG. 20 further comprising bug screens adapted for selective affixation to the body over the intake opening of each fan head and dome shaped to allow pivoting of the fan head. 